Steam pipe systems, and other fluid piping systems, are often used for the heating of buildings and other structures. Monitoring the conditions within the pipes is of vital importance for the safe and efficient working of these systems. As such, it is necessary to incorporate flow and temperature meters into the pipe systems in order to monitor the working conditions of the pipes, and associated fluids, at important locations within the system.
Modern steam meters require DC power. If available, standard AC power is easily converted to the required DC power. If not, a separate power line must be installed and maintained. To provide a suitable consistent power source, meters, and other electrical monitoring or safety devices, are generally connected to the main power supply of a building. Alternatively, other power sources, such as batteries, may be used.
In recent years, other means of generating power for electrical devices have been developed and implemented. One method involves the use of thermoelectric modules to take advantage of a temperature difference between two locations in a body, such as between the temperature within a pipe and the temperature of the surrounding atmosphere. Example devices are described in U.S. Pat. No. 4,673,863 to Swarbrick, and U.S. Pat. No. 4,095,998 to Hanson. These devices describe hollow cylindrical voltage generation devices that can be mounted onto, or replace, an exhaust pipe of an automobile. The cooling effect necessary to obtain the required temperature difference is provided by the flow of air over the external surface of the device, which is produced by the movement of the automobile. These devices appear to be suitable only for use with automobile exhausts, at least because they require significant moving air to provide the necessary cooling, and because they cannot retroactively be fitted onto a closed loop pipe system.
Another example device, for use with sub-sea drilling wells, is described in U.S. Pat. No. 5,939,667 to Oudoire et al. Again, however, the disclosed device appears to consist of a hollow cylindrical device that is coupled permanently into a piping system and cannot be retroactively fitted onto an existing closed loop pipe system.